I have done this very thing. Here is what I did:
I have an Epson Sylus R800 connected to my Mac. On the same home network, I have my work laptop, running Windows XP. I would like to print from the Windows PC to the Epson printer through the network. Sound easy? No way! I turned myself inside out trying to share the printer on the Mac with the PC using the usual Samba mechanisms. No joy. Windows steadfastly refused to recognize that there was a printer there on my Mac.
Then I stumbled across a web page on Apple.com that talked about using Bonjour to do this and thought "what have I got to lose?" and tried it out. I downloaded Bonjour for Windows, ran the very simple installer and all seemed to go well. The I opened my Windows Printers and Faxes dialog and selected Add a Printer. Boom! There is was, no muss, no fuss. My Apple based printer simply showed up, ready for selection. I was amazed! ...or "gobsmacked" as they say in the UK. Anyway, this Bonjour stuff is really neat. It truly is zero configuration networking.
OK, here are the details for those who may wish to try this themselves. The objective is to allow your Windows PC to print using a printer connected to your Mac, which is on the same network as your Mac.
1/ On the Mac, I opened System Preferences, went to Print and Fax and enabled sharing on my printer.
2/ On the Mac, I went to System Preferences, Sharing, and disabled my firewall (this step may not be needed, but I was being sure firewalling issues didn't get in the way).
3/ On my PC, I went into the corporate firewall software and added my Mac's local IP address (192.168.1.2) to the "friends" list, so that the firewall would not block communications to the Mac.
4/ On my PC, I downloaded Bonjour for Windows (get this from the Apple site at
http://www.apple.com/support/downloads/bonjourforwindows.html), and ran the installer. Living truly dangerously, I didn't even restart the PC after I installed.
5/ On the Mac, I turned on my printer - VERY important. This won't work if the printer isn't on apparently.
6/ On the PC, I ran the Bonjour Printer Wizard. A shortcut to it was placed on the desktop by the Bonjour for Windows installer. A window opened immediately and there was my printer, happily listed out and ready for use. I OK'd the preselected driver type (generic/postscript), and that was that. A few Windows progress meters popped up and disappeared as Windows installed the printer driver and then I was done.
7/ On the PC, I went to the Start Menu, selected Printers and Fax and as I mentioned above, there was my printer, ready for use.
8/ With fear and trepidation, I attempted to print a small Word document. Boom! It printed right away.
Apple makes things SO easy!!! I hope that this may make printer sharing easy for you too.